[kelvinjps]

I always wondered How YouTube distribute videos l, it's the smoothest video platform, even on when I had crappy internet it worked fine also not all.platform works well in south America.The closest to YouTube it's Netflix but lacks behinds a lot.

[majewsky]

They have cache servers deployed into the ISP networks close to your home. The ISPs allow them to do this because they also benefit from it: Their bottleneck is the connection from their own network into the wider internet backbone, and having cache servers for the big CDNs takes a huge chunk of load away from that bottleneck. Here's documentation about a similar setup for Netflix: https://openconnect.netflix.com/

[simonjgreen]

This is not a universal answer and I think deserves some correction.

1. Majority of ISPs do not host any cache for Google content

2. Credible ISPs do not have bottlenecks at the transit or peering level

3. Netflix makes use of much more local caching but their model works very differently to Youtubes

4. The concept of "internet backbone" does not really translate to reality. Peering is significantly more mesh-like than that, and transit more diverse.

Source: I have owned multiple ISPs, and still do.